null_blk: Modify the behavior of null_map_queues()

Instead of returning -EINVAL if an internal inconsistency is detected,
fall back to a single submission queue. This patch prepares for changing
the return value of the .map_queues() callbacks into void.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Keith Busch <kbusch@kernel.org>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20220815170043.19489-2-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index c451c47..5350592 100644 (file)
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -1555,7 +1555,9 @@ static int null_map_queues(struct blk_mq_tag_set *set)
                } else {
                        pr_warn("tag set has unexpected nr_hw_queues: %d\n",
                                set->nr_hw_queues);
-                       return -EINVAL;
+                       WARN_ON_ONCE(true);
+                       submit_queues = 1;
+                       poll_queues = 0;
                }
        }